1. Field
Example embodiments relate to light sensing circuits, and remote optical touch panels and image acquisition apparatuses each including the light sensing circuits, and more particularly, to light sensing circuits having a relatively simple circuit and including light-sensitive oxide semiconductor transistors as light sensing devices, and remote optical touch panels and image acquisition apparatuses each including the light sensing circuits.
2. Description of the Related Art
Touch screens are devices which allow a user to receive data on a screen by touching the screen with, for example, a finger, a pen, a stylus or the like, thereby allowing the user to perform a desired process, for example, execute a software routine in the device including the touch screen. Accordingly, touch screens may function as a combination of general display panels and/or touch panels. Such touch panels may include resistive overlay type touch panels, capacitive overlay type touch panels, surface acoustic wave (SAW) type touch panels, infrared beam type touch panels, piezoelectric type touch panels or the like.
Most touch panels operate in response to touching the panel by, for example, a finger, a pen, a stylus or the like. Accordingly, in a resistive overlay type touch panels, upper and lower conductive layers thereof may be damaged by an external pressure. In addition, such touch panels have a small size of 10 inches or less. Large-sized touch panels which may be used in a large-sized screen may not function efficiently due to a line resistance and parasitic resistance. Therefore, touch panels are currently used in small-sized and/or medium-sized display devices such as general desktop computers, laptop computers, or portable devices such as mobile phones and navigation devices, for example. As a size of the display increases, a distance between a user and the display also increases, and it may, therefore, be difficult to use touch panels in the displays.
Currently, optical touch panels have been proposed, and such optical touch panels may function by sensing light instead of sensing a touch of a finger or pen. In order to realize such optical touch panel, a relatively small sized light sensing device for sensing light is required. Also, image acquisition apparatuses such as complimentary metal oxide semiconductor (CMOS) image sensors or charge coupled devices (CCDs) require such a light sensing device for acquiring an image. Examples of the light sensing device that is generally used may include a photodiode having a PN junction structure of a semiconductor such as silicon. However, it is also difficult to increase sizes of optical touch panels and image acquisition apparatuses due to complex circuit structures.